Measurement while drilling (MWD) allows for the surface acquisition of downhole data during drilling, thereby reducing the need for costly and time consuming drill string tripping and logging/survey runs otherwise necessary to acquire downhole data.
In modern MWD systems, information is usually communicated to the surface with downhole pulsers. Pulsers generate surges or pulses in drilling fluid or mud which is flowing through a drill string. The pulses are coded so that they can be sensed or "read" at the surface. In one type of pulser, pulses are created by partially obstructing an orifice in the drill string through which the drilling mud is flowing with a signal poppet. The signal poppet is moved rapidly in and out of the orifice so that a pressure spike may be detected at the surface. Some pulsers require many moving parts and require significant amounts of power which quickly deplete the energy reserves of battery powered tools. An improved pulser is desirable.